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Marshall M Joffe

Publications and source records attributed to Marshall M Joffe.

17 recordsLinked to original sources
PubMed2006

Revisiting survival differences by race and ethnicity among hemodialysis patients: the Dialysis Outcomes and Practice Patterns Study.

Hemodialysis (HD) patients who are identified as belonging to racial or ethnic minority groups have longer survival than non-Hispanic white HD patients. This study sought to determine to what extent this survival difference is explained by comprehensive adjustment for measurable case-mix and treatment characteristics. A cohort analysis was conducted among 6677 patients between 1996 and 2001 in the American arm of the first phase of the Dialysis Outcomes and Practice Patterns Study, a prospective observational study. Using multivariable proportional hazards analysis, all-cause mortality by racial/ethnic category was compared before and after adjustment for other patient-level variables that are associated with mortality. Factors that influence the statistical associations of race/ethnicity with mortality were explored. The statistically significant (P < 0.001) associations of racial/ethnic minority categories with lower mortality in unadjusted analyses were attenuated or lost in the multivariable model. Compared with non-Hispanic white patients, the adjusted hazard ratio (HR) (95% confidence interval [CI]) for mortality was 0.86 (0.72 to 1.03) for Hispanic patients; among non-Hispanic patients, the HR (95% CI) were 0.97 (0.85 to 1.11) for black patients, 0.82 (0.56 to 1.20) for Asian patients, 0.95 (0.52 to 1.73) for Native American patients, and 0.95 (0.60 to 1.50) for patients of other races (overall P = 0.66). The survival advantages for racial/ethnic minority categories were explained most notably by the combined influence of unbalanced distributions of numerous demographic, morbidity, nutritional, and laboratory variables. The associations of race/ethnicity with survival varied little by duration of ESRD and were not influenced substantially by different rates of kidney transplantation among patients who were on HD. The survival advantages for racial and ethnic minority groups on HD are explained largely by measurable case-mix and treatment characteristics. Individual racial minority group or Hispanic patients should not be expected to survive longer on HD than non-Hispanic white patients with similar clinical attributes.

Black People↗
PubMed2006

Random effects logistic models for analysing efficacy of a longitudinal randomized treatment with non-adherence.

We present a random effects logistic approach for estimating the efficacy of treatment for compliers in a randomized trial with treatment non-adherence and longitudinal binary outcomes. We use our approach to analyse a primary care depression intervention trial. The use of a random effects model to estimate efficacy supplements intent-to-treat longitudinal analyses based on random effects logistic models that are commonly used in primary care depression research. Our estimation approach is an extension of Nagelkerke et al.'s instrumental variables approximation for cross-sectional binary outcomes. Our approach is easily implementable with standard random effects logistic regression software. We show through a simulation study that our approach provides reasonably accurate inferences for the setting of the depression trial under model assumptions. We also evaluate the sensitivity of our approach to model assumptions for the depression trial.

Humans↗
PubMed2006

Medicare coverage of tumor necrosis factor alpha inhibitors as an influence on physicians' prescribing behavior.

BACKGROUND: Rheumatoid arthritis is a chronic debilitating disease that affects 1% of the population. Tumor necrosis factor alpha inhibitors, such as etanercept and infliximab, have revolutionized the treatment of rheumatoid arthritis by averting disability but at great financial expense, generally borne by third-party payors. Prior to implementation of the Medicare Modernization Act, Medicare reimbursed for the infusion drug infliximab but not for the self-injectable drug etanercept. To determine the impact of this differential Medicare drug coverage on physicians' prescribing behavior in clinical practice, we analyzed patterns of prescribing etanercept and infliximab for patients with rheumatoid arthritis who had public insurance compared with those who had private insurance. METHODS: We conducted an observational cohort study of 1663 patients with rheumatoid arthritis newly prescribed etanercept or infliximab after enrollment in the National Databank for Rheumatic Diseases. Univariate and multivariable analyses of patient demographic and disease characteristics were conducted to characterize predictors of the biologic drug prescribed. RESULTS: Treatment groups who received etanercept and infliximab differed in 6 of 8 demographic variables and in 8 of 10 disease variables. However, stratification by type of insurance reduced many of these differences. In multivariable analyses, type of insurance plan and demographic factors were strong predictors of differential prescribing of etanercept compared with prescribing of infliximab, whereas disease characteristics generally were not. Patients with public insurance were 30% more likely to receive infliximab than those who were privately insured (P<.001). CONCLUSIONS: Public insurance predicted prescription of infliximab, reflecting preferential Medicare reimbursement for infusion drugs. Financial considerations are influential in physicians' prescription decisions. Differential drug coverage has an impact on patient care and health care costs because it influences physicians' prescribing behavior.

Age Distribution↗
PubMed2006

A potential outcomes approach to developmental toxicity analyses.

Estimating the effects of a toxin on fetal development in animal models such as mice can be problematic, because the number of pups that develop and survive until birth may simultaneously affect developmental outcomes such as birth weight and be affected by the introduction of a toxin into the fetal environment. Also, comparing pups that survived until birth at a high dose of the toxin with pups that survived at low doses may underestimate the effect of the toxin, because the lower dose means include the less healthy pups that would not survive if exposed to a higher level of toxin. We consider this problem in a potential outcomes framework that defines the effect of the dose on the outcome as the difference between what the outcome would have been for a pup had the dam in which the pup develops been exposed to dose level Z=z* rather than dose level Z=z. To disentangle the direct effect of dose from the effect of litter size, we focus on effects defined within principal strata that are a function of the survival status of the pups at each of the possible dose levels. A unique contribution to the potential outcomes literature is that we allow the outcome for a subject to be dependent on the principal stratum to which other subjects within a cluster belong.

Animals↗
PubMed2006

Macrolide resistance in adults with bacteremic pneumococcal pneumonia.

We conducted a case-control study of adults with bacteremic pneumococcal pneumonia to identify factors associated with macrolide resistance. Study participants were identified through population-based surveillance in a 5-county region surrounding Philadelphia. Forty-three hospitals contributed 444 patients, who were interviewed by telephone regarding potential risk factors. In multivariable analyses, prior exposure to a macrolide antimicrobial agent (odds ratio [OR] 2.8), prior flu vaccination (OR 2.0), and Hispanic ethnicity (OR 4.1) were independently associated with an increased probability of macrolide resistance, and a history of stroke was independently associated with a decreased probability of macrolide resistance (OR 0.2). Fifty-five percent of patients with macrolide-resistant infections reported no antimicrobial drug exposure in the preceding 6 months. Among patients who reported taking antimicrobial agents in the 6 months preceding infection, failure to complete the course of prescribed drugs was associated with an increased probability of macrolide resistance (OR 3.4).

Adolescent↗
PubMed2005

Race and electronically measured adherence to immunosuppressive medications after deceased donor renal transplantation.

Nonadherence to immunosuppressive medications may partly explain the worse allograft outcomes among black recipients of renal transplants. In a prospective cohort study of recipients of deceased donor renal transplants, microelectronic cap monitors were placed on bottles of one immunosuppressive medication to (1) measure average daily percentage adherence during the first posttransplantation year and (2) determine the factors associated with adherence. A total of 278 transplant recipients who provided sufficient microelectronic adherence data were grouped into four categories of average daily percentage adherence: 95 to 100% adherence (41.0% of patients), 80 to 95% adherence (32.4%), 50 to 80% adherence (12.9%), and 0 to 50% adherence (13.7%). In the unadjusted ordinal logistic regression model, black race was associated with decreased adherence (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.26 to 0.72; P = 0.001). Cause of renal disease, Powerful Others health locus of control, transplant center, and dosing frequency were also associated with adherence. After adjustment for transplant center and dosing frequency, the association between black race and decreased adherence was substantially attenuated (OR, 0.65; 95% CI, 0.38 to 1.14, P = 0.13). Transplant center (P = 0.003) and increased dosing frequency (OR, 0.43; 95% CI, 0.22 to 0.86, for three or four times per day dosing; OR, 2.35; 95% CI, 1.01 to 5.45, for daily dosing; versus two times per day dosing; P = 0.003) remained independently associated with adherence. Other baseline demographic, socioeconomic, medical, surgical, and psychosocial characteristics were not associated with adherence. The transplant center and dosing frequencies of immunosuppressive medications are associated with adherence and explain a substantial proportion of the race-adherence relationship.

Adult↗
PubMed2005

Rates of completion of the medical evaluation for renal transplantation.

BACKGROUND: Failure to complete the medical evaluation for renal transplantation may impede access to transplantation and preclude the possibility of preemptive transplantation. We sought to (1) characterize completion rates of the transplantation medical evaluation and (2) determine factors associated with completion of the evaluation. We hypothesized that patients not on dialysis therapy complete the evaluation process more quickly than patients receiving dialysis. METHODS: Between September 2002 and September 2003, a total of 175 patients who were evaluated for renal transplantation at the Hospital of the University of Pennsylvania were enrolled in a prospective cohort study. Patients completed a self-administered questionnaire. The progress of patients' medical evaluations, including completion of requested tests and evaluations, was extracted from the electronic medical record. RESULTS: During follow-up, 100 patients (57.1%) completed the evaluation, including tests and evaluations requested by the transplant team, whereas 49 patients (28.0%) had tests still pending. The remaining patients died (2.3%), lost interest in transplantation (1.1%), or were immediately (7.4%) or later (4.0%) declared medically ineligible for transplantation. In the multivariable Cox proportional hazards model, black race (adjusted hazard ratio, 0.63; 95% confidence interval, 0.40 to 1.00; P = 0.05) was associated with time to completion of the transplantation evaluation, but receiving maintenance dialysis at the time of the initial transplantation evaluation was not (adjusted hazard ratio, 0.92; 95% confidence interval, 0.60 to 1.42; P = 0.72). CONCLUSION: Completion of the medical evaluation for transplantation is slower in blacks than nonblacks. We were unable to detect a significant difference between dialysis and nondialysis patients in rates of completion of the evaluation.

Adolescent↗
PubMed2005

Anemia and mortality in hemodialysis patients: accounting for morbidity and treatment variables updated over time.

BACKGROUND: The objective of this study was to gain insight into the associations of anemia with mortality among maintenance hemodialysis (HD) patients and patient subgroups by an analysis that more comprehensively represents hemoglobin (Hb) level, morbidity, and treatment characteristics over time than was possible in prior observational studies. METHODS: A cohort study was conducted among 5517 subjects in the American arm of the Dialysis Outcomes and Practice Patterns Study Phase I. We used proportional hazard analysis to model all-cause mortality as a function of Hb level measured 1, 3, and 6 months previously. Forty-five potentially confounding patient-level characteristics were considered, including demographics, comorbidities, and time-updated levels of erythropoietin and parenteral iron dosing, medical events, and laboratory and dialysis measures. RESULTS: Compared to Hb 11 to <12 g/dL, subjects with Hb <11 g/dL had increased mortality [adjusted hazard ratios (95% confidence interval) in the 3-month-lagged model = 1.74 (1.24 to 2.43) for <9 g/dL, 1.25 (0.96 to 1.63) for 9 to <10 g/dL, and 1.22 (0.99 to 1.49) for 10 to <11 g/dL categories]. Mortality rates for subjects with Hb 12 to <13 g/dL and > or = 13 g/dL did not differ significantly from those with Hb 11 to <12 g/dL. The relationships between Hb and mortality varied modestly with changes in the time interval between Hb measurement and the time at risk for mortality, but did not vary according to ESRD vintage or health status indicators. CONCLUSION: Our findings confirm the associations of Hb levels > or =11 g/dL with longer survival among maintenance HD patients, but show no additional survival advantage for patients with Hb levels > or =12 g/dL. Further investigation of the relationships among anemia, treatment of anemia, and survival is warranted.

Adolescent↗
PubMed2004

Blood pressure and the survival of renal allografts from living donors.

Levels of BP have been associated with increasing rates of renal allograft failure from cadaveric donors, independent of renal function. The effect of BP, a modifiable risk factor, on the failure rates of renal allografts from living donors is unknown and maybe obscured by the rate of decline of renal function from this source of organs. A nonconcurrent cohort study collecting data from 392 recipients of a renal allograft from a living donor during 1990 to 2001 was performed. Multivariable Cox regression models were fit by means of time-varying terms for systolic BP (SBP), diastolic BP (DBP), mean arterial BP (MAP), pulse pressure, and renal function during the first year after transplantation to study the association of BP and the time to allograft failure. Potential nonlinear relationships were considered by fractional polynomial terms. Recipient gender, preemptive transplantation, and time-varying terms for the natural logarithm of creatinine clearance and acute rejection were retained in the multivariable model. Including separate multivariable models with nonlinear terms for SBP (P = 0.02), for DBP (P = 0.02), or for MAP (P = 0.05) during the first year significantly improved the fit of the respective models and confirmed that there is an association of BP and allograft failure independent of renal function. Pulse pressure had neither a linear nor nonlinear association with allograft failure. In this nonconcurrent study, the level of BP during the first year affected the survival of renal allografts from living donors, independent of renal function. Further investigation is required to confirm the level of BP that is optimal to prevent foreshortened duration of survival.

Adolescent↗
PubMed2004

Duffy antigen receptor and genetic susceptibility of African Americans to acute rejection and delayed function.

BACKGROUND: The unique distribution of the alleles for the Duffy antigen receptor complex (DARC) that binds to chemokines may be associated with the rates of acute rejection and delayed allograft function (DGF) among African Americans. METHODS: A prospective, multicenter cohort study enrolled 222 African American recipients of cadaveric renal allografts from eight adult transplant centers. Subjects were typed by allele-specific polymerase chain reaction (ASPCR) for the polymorphism at position 535 that determines the level of transcription. Associations of DARC genotypes were examined in Cox hazards models with episodes of acute rejection and in logistic regression models with the development of DGF. RESULTS: FyB Null homozygosity was observed among 67% of the recipients. Fifteen percent of the study cohort experienced at least one episode of acute rejection, and the incidence of DGF was 42.5%. The number of FyB Null alleles and FyB Null homozygosity had no detectable association with the rate of acute rejection (P > 0.50) or with the development of DGF (P > 0.50). CONCLUSION: The susceptibility of African American recipients to acute rejection and to DGF was not confirmed to be associated with DARC alleles or genotype. Future studies should exclude a potential role of donor-related DARC in transplant outcomes.

Acute Disease↗
PubMed2003

Weighting in instrumental variables and G-estimation.

We propose here a simple scheme to use information on compliance and prerandomization covariates to improve analysis of randomized trials with non-compliance. We use the data to determine the effect of randomization on treatment received among various strata defined by pretreatment covariates. When the effect of treatment received on the outcome of interest is the same across strata and pretreatment covariates predict non-compliance, weighting the estimating functions by the effect of randomization on treatment received can improve the precision of explanatory estimates of treatment effect and can increase the power of intent-to-treat tests of the null hypothesis. Efficiency gains under the weighting scheme are a simple increasing function of the variability of these weights. Such weighting schemes will often lead to improvements even when these conditions are not met. We use a randomized trial of cholestyramine to illustrate these points.

Cholesterol↗
PubMed2003

Violence does not influence early pregnancy loss.

OBJECTIVE: To examine the relationship between physical violence, controlling behavior, and spontaneous abortion (SAB). DESIGN: Nested case-control study. SETTING: Emergency department of a university hospital. PATIENT(S): One thousand one hundred ninety-nine pregnant women. MAIN OUTCOME MEASUREMENT(S): Physical violence and controlling behavior. RESULT(S): Cases experienced a SAB (n = 392) and controls maintained their pregnancy through 22 weeks (n = 807). Fifteen percent of women reported violence during the pregnancy, and 49% had reported one or more past episodes of violence. We found no relationship between any measure of physical violence (past, current, or by perpetrator) and the risk of SAB. CONCLUSION(S): Although physical violence was very prevalent in the study population, exposure to violence did not influence the risk of SAB.

Abortion, Spontaneous↗
PubMed2003

Does stress influence early pregnancy loss?

PURPOSE: The purpose of this study is to examine the relationship between stress, cortisol level and the risk for spontaneous abortion and determine the influence of stress on health-related behaviors. METHODS: Three hundred and twenty-six pregnant women presenting to the emergency department at the Hospital of the University of Pennsylvania from March 1999 through March 2000 were recruited and followed through 22 weeks gestation. Cases were women who experienced a spontaneous abortion and controls were women who maintained their pregnancy. Stress was measured by the Perceived Stress Scale (PSS), the Prenatal Social Environment Inventory (PSEI) and the Index of Spousal Abuse (ISA) prior to confirmation of spontaneous abortion. Blood samples were collected to measure cortisol and sex hormone levels. Urine samples were collected to assess cotinine, cocaine and marijuana use. RESULTS: No relationship was found between psychosocial stress, as determined by the three stress scales or cortisol level, and the risk for spontaneous abortion. Women with high stress, as measured by the PSEI, were more likely to use cigarettes and marijuana during pregnancy. High psychosocial stress during early pregnancy was not related to spontaneous abortion but high stress was associated with substance use during pregnancy. CONCLUSION: The influence of psychosocial stress on the risk of spontaneous abortion is unclear.

Abortion, Spontaneous↗
PubMed2003

The compliance score as a regressor in randomized trials.

The compliance score in randomized trials is a measure of the effect of randomization on treatment received. It is in principle a group-level pretreatment variable and so can be used where individual-level measures of treatment received can produce misleading inferences. The interpretation of models with the compliance score as a regressor of interest depends on the link function. Using the identity link can lead to valid inference about the effects of treatment received even in the presence of nonrandom noncompliance; such inference is more problematic for nonlinear links. We illustrate these points with data from two randomized trials.

Bias↗
PubMed2003

Dialysis prior to living donor kidney transplantation and rates of acute rejection.

BACKGROUND: The relationship between transplantation prior to chronic dialysis initiation and the pattern of acute rejection of kidneys from living donors (LDKT) has not been fully explored. METHODS: Using data provided by the United States Renal Data System, we performed a retrospective cohort study fitting multivariate proportional hazards models to characterize the association of chronic use of dialysis prior to transplantation [non-pre-emptive LDKT (non-PLDKT)] and acute rejection, and to examine if this association varies throughout the first year. RESULTS: Non-PLDKT was associated with a 2.5-fold higher rate of biopsy-confirmed rejection during the first month [adjusted HR 2.5, 95% confidence interval (1.85-3.33)], compared with no dialysis prior to transplantation. Increasing duration of pre-transplant dialysis was associated with increasing rate of biopsy-confirmed acute rejection during the first month (P = 0.001 for trend). Over the first year, there was a diminishing relationship between non-PLDKT and acute rejection: 2.5-, 2.22-, 2.13- and 1.78-fold elevation in the episodes of biopsy-confirmed acute rejection during the first, second, third through to the sixth and seventh through to the twelfth month post-transplant, respectively (P = 0.05 for trend). CONCLUSIONS: The waning of the association of non-PLDKT with acute rejection over time supports the hypothesis that dialysis exposure prior to transplantation may modulate the immune system to increase the rates of acute rejection.

Acute Disease↗
PubMed2003

A case-control follow-up study for disease-specific mortality.

Case-control studies often rely on subjects to report their own screening or exposure information: this information is often obtained from cases after the event of interest has occurred. This is problematic for mortality outcomes, because dead subjects cannot report the desired information. To avoid this problem, Weiss and Lazovich (1996, American Journal of Epidemiology 143, 319-322) proposed obtaining exposure or screening information from potential cases, i.e., subjects diagnosed with disease, at the time of disease diagnosis, and also from a referent series. The design is best viewed as a new scheme for sampling from a cohort. I review estimation of the effects of time-varying screening or exposure in cohort studies, using a new factorization. I then show how this factorization, together with ignorability assumptions, allows valid estimation from these new designs. Even when the sampling fraction of nondiseased subjects is unknown, causal risk ratios are estimable if diagnosis is rare in the cohort. I illustrate and compare conventional and new methods with data from the Health Insurance Plan study.

Adult↗